JP2003096224A - Production method of oscillation-restrictive bridging resin foam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method of an oscillation-restrictive bridging resin foam having excellent oscillation-restrictive property in an actually broad range of temperature. SOLUTION: In the production method of the oscillation-restrictive crosslinked resin foam, a resin composition containing at least two kinds of triblock copolymers, a polyolefin, a crosslinking agent and a foaming agent is heated for crosslinking and foaming. The triblock copolymers are preferably provided with styrene block and isoprene block having a vinyl bond. The difference in Tg between the two triblock copolymers is 10 to 40 deg.C, preferably 15 to 35 deg.C. The content of the triblock copolymers is 60 to 80 mass %, preferably 65 to 75 mass %, based on total sum content (100 mass %) of the triblock copolymers and polyolefin.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a vibration-damping crosslinked resin foam (hereinafter, also referred to as “vibration-damping foam”). More specifically, by using at least two types of specific vibration-damping resins having different glass transition temperatures (hereinafter sometimes abbreviated as “Tg”),
The present invention relates to a method for producing a vibration-damping foam having a sufficient vibration-damping property in a wide temperature range around room temperature (a temperature range of about 0 to 40 ° C.). The vibration-damping foam produced by the method of the present invention is used in various applications such as sports shoes such as athletic shoes and pads, daily necessities, wall materials and flooring materials that require vibration damping and impact resistance. can do.

[0002]

2. Description of the Related Art The damping property of a resin is due to the phenomenon that the viscoelastic behavior of the resin increases the internal friction near Tg or the second-order transition temperature and the vibration damping ability is improved. Polyurethane foam has been conventionally known as such a resin damping material. For example, JP-A-59
In Japanese Patent Publication No. 98121, it is obtained by specifying the blending amount of a foam stabilizer during the production of a flexible polyurethane foam, has both vibration damping properties and sound absorbing properties, and is useful as a ceiling material and floor material. A vibrating material is disclosed. In addition, JP-A-6
Japanese Patent Laid-Open No. 1-235418 discloses a soundproofing / damping foam formed by foaming an organic polyisocyanate and a specific polyol in the presence of a fluid acting as a foaming agent, a catalyst, a foam stabilizer and a plasticizer. ing.

As a damping material, a damping material made of a rubber foam is also known. For example, JP-A-7-62130 discloses a styrene / isoprene / styrene block polymer having sufficient vibration damping properties, a small restoration speed, excellent impact absorption properties, and good compatibility with a thermoplastic resin. A rubber foam is disclosed. Furthermore, JP-A-8-20886
No. 9 discloses a vibration-damping resin foam obtained by crosslinking and foaming a molded product made of a block copolymer of 1,2-polybutadiene having a vibration-damping property and vinyl bond-polyisoprene and polystyrene. It is disclosed. Further, in JP-A-11-349717, a triblock copolymer in which polystyrene and vinyl-polyisoprene are bonded is blended with a specific amount of a polyethylene-based resin, which is crosslinked and foamed with a foaming agent and an organic peroxide. A vibration-damping resin foam formed of the above is disclosed.

[0004]

As described above, the damping property of the resin damping material utilizes the viscoelastic behavior of the resin in the vicinity of Tg and the like. Therefore, the T
Sufficient vibration damping properties cannot be obtained in a temperature range greatly separated from g and the conventional resin vibration damping material cannot be used unless it is in a considerably narrow temperature range such as around Tg. Further, when the atmospheric temperature becomes Tg or lower, the resin becomes abruptly hard, which makes it difficult to perform processing such as cutting and cutting.

The present invention solves the above-mentioned problems of the prior art, has excellent damping properties in a wide range of practical temperature ranges, and cuts even when the ambient temperature falls below the Tg of the resin. It is an object of the present invention to provide a method for producing a vibration-damping crosslinked resin foam that does not make processing difficult.

[0006]

A crosslinked resin foam comprising at least two types of vibration-damping resins having a vinyl bond-diene block has an appropriate difference in Tg of each resin, and When the above resin is used in a specific amount ratio, it is possible to obtain a foam having excellent vibration damping property in a sufficiently wide practical temperature range. Further, by adding a predetermined amount of polyolefin to these vibration-damping resins, workability at the time of kneading and the like is improved, and an excessive increase in the viscosity of the resin composition at the time of foaming is suppressed, and the resin is sufficiently Can be expanded into the desired foam. The present invention is
It is based on such knowledge.

The method for producing a vibration-damping crosslinked resin foam of the present invention comprises at least two types of triblock copolymers having an aromatic vinyl block and a diene block having a vinyl bond, a polyolefin, a crosslinking agent and a foaming agent. It is characterized in that the contained resin composition is heated to crosslink and foam.

In the present invention, a method for producing a vibration-damping crosslinked resin foam in which the aromatic vinyl block is a styrene block and the diene block is an isoprene block can be provided. Further, when the triblock copolymer is 100% by mass, the total of any two kinds of the triblock copolymer is 80% by mass or more, and the total amount of the two kinds of triblock copolymers is 80% by mass or more. A method for producing a vibration-damping crosslinked resin foam having a glass transition temperature difference of 10 to 40 ° C. can be used. When the triblock copolymer is 100% by mass, the total of any two kinds of the triblock copolymer is 80% by mass or more, and the total amount of the two kinds of triblock copolymers is The mass ratio can be a method of producing a vibration-damping crosslinked resin foam in which one is 0.4 to 1 when one is 1. Furthermore, when the total amount of the triblock copolymer and the polyolefin is 100% by mass, the triblock copolymer is 60 to 80% by mass in the method for producing a vibration-damping crosslinked resin foam. be able to. In the present invention, a method for producing a vibration-damping crosslinked resin foam can also be used in which, after the above-mentioned crosslinking and foaming, the foam is compressed and broken to form an open-cell foam.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below.
The “triblock copolymer” includes an aromatic vinyl block and a diene block having a vinyl bond. Examples of the aromatic vinyl monomer forming the “aromatic vinyl block” include styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, 2, 4-diisopropyl styrene, 4-tert-butyl styrene, 4-cyclohexyl styrene, tert-butoxy styrene, vinyl styrene, 1-vinyl naphthalene, etc. are mentioned.
Further, as the diene-based monomer forming the above-mentioned "diene block", isoprene, 1,3-butadiene, 2,3
-Dimethyl-1,3-butadiene, chloroprene and the like can be mentioned.

The aromatic vinyl monomer and the diene monomer are not particularly limited, but as the aromatic vinyl monomer, styrene, 2-methylstyrene, 3-methylstyrene, 4
-Cyclohexylstyrene, vinylstyrene, 1-vinylnaphthalene and the like are preferable, and styrene is more preferable.
Furthermore, as the diene-based monomer, isoprene, 1,3-
Butadiene, chloroprene and the like are preferable, and isoprene is more preferable. Thus, a triblock copolymer including a styrene block and an isoprene block having a vinyl bond is particularly preferable because it has excellent vibration damping properties.

In the present invention, at least two kinds of triblock copolymers are used, and 10 triblock copolymers are used.
When the amount is 0% by mass, the total of any two kinds of triblock copolymers is 80% by mass or more, and the difference between the glass transition temperatures of these two kinds of triblock copolymers is 1 or less.
It is preferably 0 to 40 ° C., particularly 15 to 35 ° C.
This makes it possible to obtain a vibration-damping foam having a sufficient vibration-damping property in a wide practical temperature range. When the difference in Tg is less than 10 ° C., it may not be possible to obtain a vibration-damping foam having practical vibration-damping properties in a sufficiently wide temperature range, which is not preferable. On the other hand, if the difference in Tg exceeds 40 ° C., the temperature range where sufficient vibration damping property is obtained is not continuous, and the vibration damping property tends to be insufficient near the intermediate temperature, which is not preferable.

If the total amount of the two types of triblock copolymers is less than 80% by mass, a wide range of practical temperatures can be obtained depending on Tg of other triblock copolymers or the content of vinyl bonds in diene blocks. In some cases, it may not be possible to obtain a vibration-damping foam having sufficient and stable vibration-damping properties.

The content of vinyl bonds contained in the diene block of the triblock copolymer is not particularly limited, but may be 20 to 20.
It is preferably 70%, especially 30 to 60%. If this content is less than 20%, crosslinking is difficult to proceed and the bending strength and the like of the vibration-damping foam tends to decrease, such being undesirable. On the other hand, if it exceeds 70%, crosslinking may proceed excessively before foaming, the viscosity of the resin composition may increase, the resin may not expand sufficiently, and a desired foam may not be obtained. Further, in order to obtain a vibration-damping foam having excellent vibration-damping properties in a practical temperature range, the content of vinyl bonds is such that the glass transition temperature of the triblock copolymer is 0 ° C. to room temperature (20 to 4).
The temperature is adjusted to about 0 ° C.) and is preferably 30% or more, and particularly preferably 40% or more.

Further, when the triblock copolymer is 100% by mass, the total of any two kinds of triblock copolymers is 80% by mass or more, and the mass of these two kinds of triblock copolymers is When one of the ratios is 1, the other is 0.4 to 1, particularly 0.6 to 1, and more preferably 0.8 to 1. When this mass ratio is less than 0.4,
It becomes a vibration-damping foam having only the vibration-damping property due to one of the triblock copolymers having a high mass ratio, and can be a vibration-damping foam having continuous and sufficient vibration-damping properties in a wide practical temperature range. It is not possible and not preferable.

If the total amount of the two types of triblock copolymers is less than 80% by mass, a wide range of practical temperatures may be used depending on the Tg of the other triblock copolymers or the content of vinyl bonds in the diene block. In some cases, it may not be possible to obtain a vibration-damping foam having sufficient and stable vibration-damping properties.

As the above-mentioned "polyolefin", a crystalline polyolefin is used, or a crystalline polyolefin and an amorphous polyolefin are used in combination. The crystalline polyolefin is not particularly limited, but polyethylene, ethylene-propylene copolymer, ethylene-butene-1 copolymer, ethylene-vinyl acetate copolymer, ethylene-acryl produced by a high-pressure method, a medium-pressure method or a low-pressure method is used. A copolymer or the like with a methyl, ethyl, propyl or butyl ester of an acid (the content of this ester is preferably 45 mol% or less) can be used. The crystallinity of this crystalline polyolefin is not particularly limited,
The crystallinity measured by X-ray diffractometry is preferably 30% or more, particularly 50% or more. These crystalline polyolefins may be used alone or in combination of two or more.

In the case of forming an open-cell foam, an ethylene vinyl acetate copolymer, a crystalline polyolefin,
It is preferable to use an ethylene-acrylic acid ester copolymer or the like. When these copolymers are used, the strength of the resin film of the vibration damping foam becomes appropriate, the foaming by compression, pressing, etc. is easy, and the shape is easily recovered after the foaming, and the homogenization is uniform. It can be an open cell foam.

The amorphous polyolefin is not particularly limited, either.
Amorphous and relatively low molecular weight polyolefins can be used. Examples of the amorphous polyolefin include polypropylene, propylene-ethylene copolymer, propylene-butene-1 copolymer and the like, which may be modified with unsaturated carboxylic acid and its derivative. The crystallinity of the amorphous polyolefin is not particularly limited, but the crystallinity measured by X-ray diffractometry is preferably 1% or less, particularly 0.5% or less. These amorphous polyolefins may be used alone or in combination of two or more.

The amorphous polyolefin is 2.5 to 30 parts by mass, particularly 3 to 15 parts by mass, and further 5 to 10 parts by mass, when the total amount of the crystalline polyolefin and the amorphous polyolefin is 100 parts by mass. It is preferable to set it as a part. When the amount of the amorphous polyolefin is less than 2.5 parts by mass, the foamed body is made into an open-cell foam, so that when the closed cells are formed into open cells, it is difficult for the outside of the foam to break and a homogeneous open-cell foam is obtained. Tend to be unable to. On the other hand, when the amount exceeds 30 parts by mass, the adhesiveness of the foam becomes large, and the foam may adhere to a device such as a roll when the foam is broken, which may lower the workability.

The mass ratio of the triblock copolymer and the polyolefin is not particularly limited, but when the total amount of the triblock copolymer and the polyolefin is 100% by mass, the triblock copolymer has a content of 60 to 60%. It is preferably 80% by mass, particularly preferably 65 to 75% by mass. When the blending amount of the triblock copolymer is less than 60% by mass, it tends to be impossible to obtain a vibration damping foam having sufficient vibration damping properties. On the other hand, when the blending amount exceeds 80% by mass, the blending amount of the polyolefin becomes too small, the processability at the time of kneading, etc. is lowered, and the viscosity of the resin composition at the time of foaming is increased so that the resin is sufficiently expanded. In some cases, the desired foam cannot be obtained.

The above-mentioned "resin composition" includes, in addition to the triblock copolymer, the crystalline polyolefin and the amorphous polyolefin optionally used, various polymers which do not impair the vibration damping property. It may be. Such polymers include natural rubber, styrene-butadiene rubber,
Liquid polybutadiene etc. are mentioned. The blending amount of these resins is preferably 10 parts by mass or less, and particularly preferably 5 parts by mass or less, when the total amount of the triblock copolymer and the polyolefin is 100 parts by mass.

As the above-mentioned "crosslinking agent", dicumyl peroxide (manufactured by NOF CORPORATION, trade name "Parkmill D", etc.), 2,5-dimethyl-2,5-bis-tert.
-Butylperoxyhexane, 1,3-bis-tert
-Butylperoxy-isopropylbenzene, 2,5-
Dimethyl-2,5-di-tert-butylperoxyhexane (manufactured by NOF CORPORATION, trade name "Perhexa 25
B "and the like), n-butyl-4,4-bis-tert-butyl peroxyvalerate (manufactured by NOF CORPORATION, trade name" Perhexa V ", etc.) and the like. These may be used alone or in combination of two or more.

The amount of the cross-linking agent to be blended is 0.1 to 2 parts by mass, particularly 0.1 to 1 part by mass, and further 0 if the total amount of the triblock copolymer and the polyolefin is 100 parts by mass. It is preferably from 0.2 to 0.7 parts by mass. If the compounding amount of the cross-linking agent is less than 0.1 part by mass, the gas generated by the decomposition of the foaming agent may not be retained, and the resin tends not to expand sufficiently. On the other hand, when the amount exceeds 2 parts by mass, the viscosity of the resin composition is too high and the strength of the resin film becomes too large, and it is not easy to break the bubbles due to compression and pressing.
When forming an open-cell foam, it cannot be a homogeneous foam.

The above-mentioned "foaming agent" can be used without particular limitation as long as it decomposes at a temperature equal to or higher than the melting points of the triblock copolymer and the polyolefin. Examples of such a foaming agent include azodicarbonamide, dinitrosopentamethylenetetramine, 4,4-oxybisbenzenesulfonyl hydrazide, hydrazodicarbonamide, barium azodicarboxylate, trinitrotrimethyltriamine, sodium citrate, hydrogen carbonate. Sodium and the like can be mentioned. These may be used alone or in combination of two or more.

The blending amount of the foaming agent is 1 to 15 parts by mass, particularly 1 to 10 parts by mass, and further 2 to 100 parts by mass based on 100 parts by mass of the triblock copolymer and the polyolefin.
It is preferably 8 parts by mass. If the blending amount of the foaming agent is less than 1 part by mass, the foaming may not be sufficiently performed, and a foam having a required foaming ratio or the like may not be obtained. On the other hand, if it exceeds 15 parts by mass, it tends to be excessively foamed and a homogeneous foam having excellent appearance and the like cannot be obtained.

The method for preparing the resin composition in which the triblock copolymer and the polyolefin are mixed with a crosslinking agent, a foaming agent and the like is not particularly limited, and a single-screw or twin-screw extruder, a Banbury mixer, a pressure kneader and a twin kneader can be used. It can be prepared by a device generally used for compounding and kneading resins, elastomers, etc., such as a shaft roll.

The vibration-damping foam is prepared by filling the resin composition in a mold, heating and pressurizing it to decompose the crosslinking agent and the foaming agent, and then depressurizing the resin composition at a desired time. It can be produced by a so-called one-step foaming method, which is a foam having a foaming ratio. In addition, the resin composition is filled in a primary mold and heated under pressure for primary expansion, and then the formed intermediate foam is filled in a secondary mold and heated under normal pressure for secondary expansion. It can also be produced by a so-called two-stage foaming method, which is a final foam having a desired expansion ratio.

As a manufacturing apparatus for a mold or the like, one conventionally used in manufacturing a resin foam can be used. The pressure, temperature and the like can be appropriately set depending on the physical properties of the resin and the types of the foaming agent and the cross-linking agent. Furthermore, in order to control the foaming state of the vibration damping foam, a compound containing urea as a main component, zinc oxide, a metal oxide such as lead oxide,
Foaming aids such as lower or higher fatty acids such as hexanoic acid and stearic acid or metal salts thereof can be added. Further, for the purpose of improving the physical properties, carbon black, titanium oxide or the like may be blended, and other colorants,
An ultraviolet absorber, a flame retardant, a crosslinking aid, etc. can also be used.

The vibration damping foam produced by the method of the present invention is usually a closed cell foam having a high closed cell rate.
Depending on the application, open cell foaming may be preferable, and in this case, the closed cell foam can be compressed and ruptured to give an "open cell foam". The method of compressing and breaking the bubbles is not particularly limited, but the closed-cell foam is usually compressed to about 1/5 to 1/2 by a method of inserting between a pair of rolls such as a constant velocity biaxial roll. By doing so, the bubbles can be easily broken. In addition, the open-cell foam means ASTM D 2856.
It means that the closed cell ratio measured according to the above is 20% or less, and the closed cell foam means that the closed cell ratio measured in the same manner is 50% or more.

[0030]

EXAMPLES The present invention will be specifically described below with reference to examples. (1) Production of vibration-damping crosslinked resin foam (Experimental Examples 1 to 7) A mixture in which the total of resin components was 100 parts by mass, and the following respective components were blended at the mass ratios shown in Table 1, The resin composition was kneaded with a kneader at 100 ° C. for 20 minutes, and then with a biaxial mixing roll at 100 ° C. for 10 minutes. Then, it is filled in a mold heated to 150 ° C., heated under a pressure of 10 MPa for 40 minutes to crosslink,
A vibration-damping crosslinked resin foam was produced by foaming.

(2) Raw material component (a) Triblock copolymer Styrene / vinyl bond-isoprene / styrene triblock copolymer (Kuraray Co., Ltd., trade name "HYBLER 5127", Tg; 8 ° C, vinyl bond content 60% or more) Styrene / vinyl bond-isoprene / styrene triblock copolymer (Kuraray Co., Ltd., trade name "HIBLER 5125", Tg; -19 ° C, vinyl bond content; 50
%) (B) Polyolefin: Crystalline low-density polyethylene (manufactured by Tosoh Corporation, trade name "Petrosene 170") (c) Crosslinking agent: Dicumyl peroxide (manufactured by NOF Corporation, trade name "Parkmill D") ( d) Foaming agent: Azodicarbonamide (manufactured by Eiwa Kasei Co., Ltd., trade name "Vinihol AC # 3") (e) Foaming aid; Second-class zinc white zinc stearate urea system (manufactured by Eiwa Kasei Co., Ltd., trade name "Cellpaste 101") (f) Antioxidant (Ciba Specialty Chemicals, trade name "Irganox 1010")

(3) Evaluation of vibration damping property Viscoelasticity measuring device (manufactured by Rheometrics Far East Co., Ltd., model "Dynamic Analyzer RDA70"
0 "), the measurement was performed at a frequency of 11 Hz.
The damping property of each damping foam was evaluated by tan δ. The results are also shown in Table 1. If tan δ is in the range of 0.08 to 0.7, it can be said that the vibration damping foam has sufficient vibration damping properties.

[0033]

[Table 1]

According to the results shown in Table 1, the vibration-damping foams of Experimental Examples 1 to 4 in which two types of triblock copolymers having a Tg difference of 27 ° C. were used in a preferable mass ratio, were 0 ° C. and 25
It can be seen that tan δ is in the range of 0.08 to 0.7 at any temperature of 0 ° C., and that it has sufficient vibration damping properties in a wide range of practical temperature ranges. On the other hand, the vibration-damping foam of Experimental Example 5 in which only one type of triblock copolymer was used, and the vibration-damping foams of Experimental Examples 6 to 7 in which the mass ratio of the two types of triblock copolymers was not within the preferred range. Then, it can be seen that either tan δ of 0 ° C. or 25 ° C. is very small, and the temperature range in which the vibration damping property is obtained is narrow.

[0035]

According to the method for producing a vibration-damping crosslinked resin foam of the present invention, it is possible to easily obtain a vibration-damping foam having excellent vibration-damping properties in a wide range of practical temperature ranges. Furthermore,
Using a triblock copolymer consisting of specific monomers,
In particular, when the difference in Tg between the two types of triblock copolymers is within the preferable range, it is possible to produce a vibration damping foam having more excellent vibration damping properties. Further, by specifying the mass ratio of the two kinds of triblock copolymers and the mass ratio of the triblock copolymer in the total of the resins, the vibration damping foam having more excellent vibration damping property. Can be manufactured. Furthermore, the obtained vibration-damping foam can be used in applications requiring breathability such as sports equipment by forming it into an open-cell foam by a simple method of compression. The body can be easily manufactured.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F16F 1/37 F16F 1/37 Z 15/02 15/02 Q F term (reference) 3J048 AA01 BD02 BD04 3J059 AD05 BC04 EA06 GA50 4F074 AA08B AA09B AA17 AA20 AA24 AA24A AA25A AA26A AA32B BA13 BA16 BA18 BA19 BA28 BB02 CD01 DA08 DA12 DA13 DA40 4J002 BB03Y BB05Y BB00Y BB00Y BB01Y BB17Y BB17Y BB17Y BB17Y BB17Y BB17Y BB17Y BB17Y BB17Y

Claims (6)

[Claims] 1. A resin composition containing at least two triblock copolymers having an aromatic vinyl block and a diene block having a vinyl bond, a polyolefin, a crosslinking agent and a foaming agent is heated to crosslink and foam. A method for producing a vibration-damping crosslinked resin foam, comprising: 2. The method for producing a vibration-damping crosslinked resin foam according to claim 1, wherein the aromatic vinyl block is a styrene block and the diene block is an isoprene block. 3. When the triblock copolymer is 100% by mass, the total of any two kinds of the triblock copolymer is 80% by mass or more, and the two triblock copolymers are The difference between the glass transition temperatures of the polymers is 10
It is -40 degreeC, The manufacturing method of the vibration damping crosslinked resin foam of Claim 1 or 2. 4. When the triblock copolymer is 100% by mass, the total of any two kinds of the triblock copolymer is 80% by mass or more, and the two triblock copolymers are The method for producing a vibration-damping crosslinked resin foam according to any one of claims 1 to 3, wherein one of the polymers has a mass ratio of 0.4 to 1 when the other has a mass ratio of 1. 5. The triblock copolymer is 60 to 80 mass% when the total of the triblock copolymer and the polyolefin is 100 mass%.
5. The method for producing a vibration-damping crosslinked resin foam according to any one of items 1 to 4. 6. The production of a vibration-damping crosslinked resin foam according to any one of claims 1 to 5, wherein after the crosslinking and foaming, the foam is compressed and ruptured to form an open-cell foam. Method.